Taxol enhancer compounds

Disclosed is a compound represented by the Structural Formula (I): Y is a covalent bond, a phenylene group or a substituted or unsubstituted straight chained hydrocarbyl group. In addition, Y, taken together with both >C═Z groups to which it is bonded, is a substituted or unsubstituted aromatic group. Preferably, Y is a covalent bond or —C(R 7 R 8 )—. R 1 and R 2 are independently an aryl group or a substituted aryl group, R 3 and R 4 are independently —H, an aliphatic group, a substituted aliphatic group, an aryl group or a substituted aryl group. R 5 -R 6 are independently —H, an aliphatic group, a substituted aliphatic group, an aryl group or a substituted aryl group. R 7 and R 8 are each independently —H, an aliphatic or substituted aliphatic group, or R 7 is —H and R 8 is a substituted or unsubstituted aryl group, or, R 7 and R 8 , taken together, are a C2-C6 substituted or unsubstituted alkylene group. Z is ═O or ═S. Also disclosed are pharmaceutical compositions comprising the compound of the present invention and a pharmaceutically acceptable carrier or diluent. Also disclosed is a method of treating a subject with cancer by administering to the subject a compound of Structural Formula (I) in combination with taxol or an analog of taxol.